Will this diffuser scrape on steep driveway approaches or speed bumps?

Rear diffusers sit lower than OEM bumpers and add depth to the rear fascia. Measure your current ride height and driveway approach angles before installation. If you frequently bottom out at steep inclines, verify clearance on your specific vehicle height and suspension setup.

Is this diffuser purely cosmetic or does it actually improve aerodynamics?

The Waterman design includes functional underbody channels and fin geometry intended to manage airflow separation and reduce lift at speed. Real-world aero benefit depends on your driving conditions, speed, and how the diffuser integrates with your complete rear bumper assembly. Treat it as a styled component with aero intent rather than a track-focused engineering part.

What prep work is needed before painting or coating?

Sand and prep the surface thoroughly to remove any release agent residue and create tooth for primer adhesion. Follow your chosen primer and paint system's surface preparation guidelines. Proper prep is essential for long-term adhesion and finish durability.